This invention relates to a water heating apparatus and more specifically to such combustion chambers used in such water heaters.
In gas water heaters liquid condensate is produced as a natural by-product of the combustion process. In the past this condensate has been collected in the combustion chamber, e.g. U.S. Pat. No. 2,480,657 to Jones and U.S. Pat. No. 2,650,575 to Carlson, where it is vaporized by the gas flame.
However, in high efficiency water heaters, vaporization of the condensate is not desirable. Since the heat of vaporization is approximately 540 cal./gm., each gram of condensate that is changed to steam consumes 540 calories of heat that could otherwise be used to heat the water in the tank. In high efficiency systems this waste cannot be tolerated.
Also in the past combustion chambers, such as that shown in U.S. Pat. No. 2,480,657 to Jones, consisted of a cylindrical casing that contained the combustion flame and a vertical flue leading up from the combustion chamber.
However, it has been found that the amount of heat transferred from the combustion chamber to the surrounding water in the tank is proportional to the speed of the combustion gases as they travel from the ignition area to the flue. Therefore it is desirable to accelerate the combustion gases as they journey towards the flue.